JP2000152552A - Spindle motor for driving recording disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle motor for driving a recording disk which can prevent dislocation of pre-load at the time of temperature change which is generated in the case that rolling elements made of ceramic are used. SOLUTION: This spindle motor is equipped with a shaft member 12 and a rotor hub 4 retained by the shaft member 12 via a pair of bearings 14, 16. The rotor hub 4 is provided with a hub main body 30, and a bearing retaining sleeve 32 arranged in the radial direction inside the hub main body 30. One end portion of the sleeve 32 is fixed to the hub main body 30. Between the other end portion of the sleeve 32 and the hub main body 30, an annular interval 64 is formed. An outer ring 22 of the bearing 14 is installed on the hub main body 30, and an outer ring 24 of the bearing 16 is installed on the other end side of the sleeve 30. The coefficient of thermal expansion of the sleeve 32 is larger than that of the shaft member 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for rotating a recording disk such as a hard disk.

[0002]

2. Description of the Related Art A conventional spindle motor used for rotating a recording disk such as a hard disk is
A shaft member fixed to a base member or a bracket attached to the base member of the recording disk drive device, a rotor hub rotatable relative to the shaft member, and a pair of shaft members interposed between the shaft member and the rotor hub; The rotor hub includes a bearing, a rotor magnet mounted on the rotor hub, and a stator disposed opposite to the rotor magnet. One or more recording disks are mounted on the rotor hub.

In such a spindle motor,
Generally, the shaft member is made of stainless steel (for example, SUS430).
F) and the rotor hub is made of stainless steel (for example, SUS430F), aluminum (for example, A6061)
Or it is formed from an aluminum alloy. Further, a pair of bearings for rotatably supporting the rotor hub includes an inner ring and an outer ring and a ball as a rolling element interposed between the inner ring and the outer ring, and the inner ring, the outer ring and the ball are formed of bearing steel (for example, SU).
J2).

In recent years, as recording disk drives have been increasingly required to be reduced in size, increased in speed, and increased in capacity, in order to increase the recording capacity per unit area of the recording disk, magnetic characteristics have been reduced. An excellent thin film magnetic head and a magnetic head using an MR element whose internal resistance changes depending on the magnitude of a magnetic field have been adopted. In the case of a recording disk drive using a magnetic head using such an MR element, a constant voltage is applied to the magnetic head due to the characteristics of the MR element. As a result, a potential difference occurs between the recording disk and the magnetic head, and when the magnetic head floats from the recording disk, a discharge occurs between the recording disk and the magnetic head, which destroys information recorded on the recording disk, It has the disadvantage that the magnetic head is electrically corroded.

[0005] Also, with the spindle motor for rotating the recording disk, the bearing using a conventional steel ball (rolling element) has a problem of play due to wear of the steel ball, vibration, The problem of contamination of the clean space in the recording disk drive due to the generation of dust due to the wear, the problem of ball seizure, and the like have arisen.

In order to prevent the above-mentioned discharge between the recording disk and the magnetic head, for example, Japanese Unexamined Patent Publication No.
In Japanese Patent Application Publication No. 3 (1993) -1995, at least one of an inner ring, an outer ring and a rolling element of a bearing for rotatably supporting a rotor hub is formed of ceramic, and a base member of the recording disk drive and the rotor hub are electrically insulated. Means for doing so are disclosed. Above all, by configuring the ball as a rolling element interposed between the inner and outer rings with ceramic, electrical insulation between the base member and the rotor hub is ensured, and at the same time the use of a ceramic ball having high hardness, Problems such as generation of backlash and vibration due to wear of the ball, seizure of the ball, generation of dust, and the like can also be solved.

[0007]

However, for example, when the balls of the members constituting the bearing are formed of ceramic and the inner and outer rings are formed of the same bearing steel as in the prior art, the temperature in the recording disk drive rises. When the shaft member, the rotor hub, and the bearing thermally expand, the coefficient of thermal expansion between the ball formed of ceramic and the other member is significantly different, so that a gap is generated between the inner and outer rings and the ball, and the pair of bearings A state in which no preload is applied, that is, a state in which so-called preload is released, causes a rotation runout and the like in the rotor hub, which causes a problem that the rotation characteristics are deteriorated.

The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a temperature change occurring when a bearing having a ceramic rolling element is used. It is an object of the present invention to provide a recording disk drive spindle motor capable of preventing a loss of preload at the time of rotation and stably rotating a rotor hub.

[0009]

According to the present invention, a shaft member fixed to a base member of a recording disk drive or a bracket attached thereto, a rotor hub to which at least one recording disk is mounted, and the shaft member A recording medium comprising: a pair of bearings disposed at intervals in the axial direction between the rotor hub and the rotor hub; a rotor magnet mounted on the rotor hub; and a stator disposed facing the rotor magnet. In the disk drive spindle motor, the rotor hub has a hub main body on which the recording disk is mounted, and a bearing support sleeve disposed radially inside the hub main body, and one end of the bearing support sleeve has An annular surface is fixed between the inner peripheral surface of the hub body and the outer peripheral surface of the other end of the bearing support sleeve and the inner peripheral surface of the hub body. A gap is formed, and each of the pair of bearings includes an inner ring and an outer ring that are disposed at an interval in the radial direction, and a plurality of ceramic rolling elements interposed between the inner ring and the outer ring. The outer ring of one of the pair of bearings is mounted on the hub body, and the outer ring of the other bearing is mounted on the other end of the bearing support sleeve. An expansion coefficient is larger than a thermal expansion coefficient of the shaft member, and when a temperature rises, an axial thermal expansion of the bearing support sleeve is larger than an axial thermal expansion of the shaft member.

According to the present invention, the rotor hub comprises a hub body and a bearing support sleeve, one end of the bearing support sleeve is fixed to the hub body, and the other outer peripheral surface of the bearing support sleeve and the inner circumference of the hub body. An annular gap is formed between the two surfaces. With this configuration, the other end of the bearing support sleeve can freely expand and contract in the axial direction due to a temperature change. The gap between the hub body and the bearing support sleeve is formed in such a size that the two do not substantially contact each other even due to a temperature change, and by forming such a size, free expansion and contraction of the other end side of the bearing support sleeve is achieved. Permissible.

The outer ring of one of the pair of bearings is mounted on the hub body, and the outer ring of the other bearing is mounted on the other end of the bearing support sleeve. The position of the outer ring of one bearing will change somewhat. In this spindle motor, the coefficient of thermal expansion of the bearing support sleeve is larger than the coefficient of thermal expansion of the shaft member.
With reference to one bearing, the outer ring of the other bearing is displaced somewhat axially outward from its inner ring, that is, in a direction in which the gap generated in the radial direction is corrected by the axial displacement, and thus the ceramic rolling element is moved. It is possible to prevent the pre-load of the provided bearing from dropping at a high temperature. Further, the present invention is characterized in that an annular shoulder portion acting on the outer ring of the other bearing is provided on the inner peripheral surface on the other end side of the bearing support sleeve.

According to the present invention, an annular shoulder is provided on the inner peripheral surface on the other end side of the bearing support sleeve, and the outer ring of the other bearing is mounted so as to abut this annular shoulder. Therefore, when the other end side of the bearing support sleeve thermally expands due to a rise in temperature, the annular shoulder acts on the outer ring of one of the bearings, so that it can be reliably displaced in the axial direction. Further, in the present invention, an annular groove is formed on an outer peripheral surface of a portion between the fixed portion of the bearing support sleeve and the annular shoulder portion.

According to the present invention, since the annular groove is formed on the outer peripheral surface of the bearing support sleeve, the bearing support sleeve is easily bent in the axial direction, and a predetermined preload is applied to the pair of bearings by such elastic bending. The preload applying effect to be applied and the preload maintaining effect to maintain a predetermined preload at a high temperature are improved.

Further, in the present invention, one end of the bearing support sleeve is fixed to the hub body in the vicinity of a bearing on a base side of the shaft member among the pair of bearings.

According to the present invention, since one end of the bearing support sleeve is fixed to the hub body near the bearing on the base side of the bearing, the axial length of the bearing support sleeve is sufficiently ensured. At a high temperature, the outer ring of the other bearing can be displaced as required to reliably prevent the preload of the pair of bearings from being released.

In the present invention, a fixed projection protruding inward in the radial direction is provided at a predetermined portion of the inner peripheral surface of the hub main body, and an outer ring of a bearing on a base side of the shaft member is provided with the fixed projection. The bearing support sleeve is positioned to abut on the other end surface of the fixed protrusion, and the bearing support sleeve is fixed to the inner peripheral surface of the fixed protrusion. I do.

According to the present invention, the outer ring of the bearing at the base side of the shaft member is in contact with one end of a fixed projection provided on the inner peripheral surface of the hub, and the bearing support sleeve is connected to the other end of the fixed projection. Because of the contact, the bearing and the bearing support sleeve can be positioned at predetermined positions with respect to the hub body. In addition, since the bearing support sleeve is fixed to the inner peripheral surface of the fixing protrusion with which the outer ring of the bearing abuts, the distance between the fixing portion of the bearing support sleeve and the outer ring of the bearing mounted on the bearing support sleeve should be increased. Can be.

Further, in the present invention, an axial distance (L) between a fixing portion of the bearing support sleeve and the hub main body and the outer ring of the other bearing is defined as follows, where d is the diameter of the rolling element. 0.85d ≦ L ≦ 7.83d is set.

According to the present invention, the distance (L) between the fixed portion of the bearing support sleeve and the hub body and the outer ring of the other bearing is set to 0.85d ≦ L ≦ 7.83d (d: diameter of the rolling element). Therefore, the clearance between the bearings caused by the temperature rise can be corrected by the displacement in the axial direction, and the preload can be prevented from falling off.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a recording disk drive spindle motor according to the present invention will be described with reference to the accompanying drawings. First Embodiment FIG. 1 is a sectional view showing a first embodiment of a spindle motor according to the present invention. Referring to FIG. 1, the spindle motor includes a bracket 2 and a rotor hub 4 rotatable relative to the bracket 2, and the bracket 2 is a base of a recording disk drive such as a hard disk drive. It is attached to a member (not shown) as required. The bracket 2 includes a circular bracket main body 6, a peripheral side wall 8 extending upward is provided on an outer peripheral portion of the bracket main body 6, and a flange 10 extending radially outward is provided at an upper end of the peripheral side wall 8. Then, the flange 10 is attached to the base member.

A shaft member 12 is provided at the center of the bracket body 6.
Is fixed by, for example, press-fitting, and the other end (upper end) extends upward from the bracket body 6. In this embodiment, the shaft member 12 is attached to the bracket 2 and the bracket 2 is attached to a base member (not shown). However, the present invention is not limited to this. It can also be attached to a member.

The shaft member 12 has a pair of ball bearings 1 spaced apart in the axial direction of the motor, that is, in the vertical direction in FIG.
The rotor hub 4 is rotatably supported via the bearings 14 and 16. Ball bearings 14,
Numeral 16 is substantially the same configuration, and as inner races 18, 20 and outer races 22, 24 arranged at intervals in the radial direction, and as rolling elements interposed between the inner races 18, 20 and outer races 22, 24. Of the inner rings 18, 20
Are mounted on the shaft member 12 by, for example, an adhesive (and / or press-fit), and the outer races 22, 24 are mounted on the rotor hub 4 side by, for example, an adhesive (and / or press-fit). The bearings 14 and 16 and the configuration related thereto will be described later.

The illustrated rotor hub 4 has a cylindrical hub body 3.
0 and a bearing support sleeve 32 disposed inside the hub body 30 in the radial direction. Hub body 30
An annular flange 34 protruding radially outward at the lower end of the
A recording disk (not shown) such as a hard disk is mounted on the upper surface of the annular flange 34, and one or a plurality of recording disks (in the case of a plurality of disks, a spacer is provided between adjacent recording disks). The recording disk (interposed) is attached to the hub body 30. The bearing support sleeve 32 and the configuration related thereto will also be described later.

A yoke member 36 is provided at the lower end of the hub body 30.
Is installed. The yoke member 36 has a peripheral side wall 38 and a mounting flange 40 extending radially inward from the upper end of the peripheral side wall 38.
Is attached to the lower end of the housing by, for example, caulking. An annular rotor magnet 42 is mounted on the inner peripheral surface of the peripheral side wall 38 of the yoke member 36, and a stator 44 is disposed radially inward facing the rotor magnet 40. The stator 44 includes a stator core 46 formed by stacking core plates, and a coil 48 wound around the stator core 46 as required.
The stator core 46 is attached to a boss 50 provided on the bracket body 6.

In one (lower) bearing 14, that is, in this embodiment, a bearing on the base side of the shaft member 12, a seal member 52 is attached to one end of the outer ring 22.
The tip 2 extends toward the inner ring 18 to seal a space between the outer ring 22 and the inner ring 18. In the other (upper) bearing 16, that is, in the present embodiment, at the tip end side of the shaft member 12, similarly to the one bearing 14, a seal member 54 is attached to the outer race 24, and the seal member 5 is provided.
4 has a tip portion extending toward the inner ring 20 to seal a space between the outer ring 24 and the inner ring 20. A magnetic fluid sealing means 56 is provided axially outside of the other bearing 16, and a cap member 58 for preventing scattering of the magnetic fluid is provided further outside the magnetic fluid sealing means 56,
The magnetic fluid sealing means 56 and the cap member 58 are mounted on the rotor hub 4 side.

In this spindle motor, a driving current is supplied to the coil 48 of the stator 44. When the driving current is supplied, the stator 44 is magnetized, and the stator 44 is magnetized.
The rotor hub 4 and a recording disk (not shown) mounted thereon are driven to rotate in a predetermined direction by a mutual magnetic action between the rotor hub 42 and the rotor magnet 42.

Next, the pair of bearings 14 and 16, the bearing support sleeve 32, and the configuration related thereto will be described. In the pair of bearings 14 and 16, balls 26 and 28 as rolling elements are formed of a ceramic material in order to provide sufficient wear resistance. For example, silicon nitride (Si ₃ N ₄ ), alumina (Al ₂ O ₃ )
Are used. The inner rings 18, 20 and the outer rings 22, 24 of the bearings 14, 16 are made of, for example, bearing steel (for example, S
UJ2). The balls 26, 28 of the bearings 14, 16 are rotatably held by a retainer (not shown) made of, for example, a synthetic resin.

In such bearings 14 and 16, when the plurality of balls 26 and 28 are formed of, for example, silicon nitride (or alumina), and the inner rings 18, 20 and the outer rings 22, 24 are formed of, for example, bearing steel, nitriding is performed. Silicon (or alumina) has a thermal expansion coefficient of 3.4 × 10 ⁻⁶ / ° C. (or 7.5 to 7.8 × 10 ⁻⁶ / ° C.), while the bearing steel has a thermal expansion coefficient of 12. Since it is 5 × 10 ⁻⁶ / ° C., when the temperature of the recording disk drive rises and the spindle motor becomes hot, the inner races 18 and 20 and the outer race 2
Due to the difference in thermal expansion between the balls 2 and 24 and the plurality of balls 26 and 28, a gap is formed between them, and the preload of the bearings 14 and 16 tends to decrease. As a result, the reduction of the preload is prevented, and the occurrence of backlash and vibration is also prevented.

More specifically, at one end of the inner peripheral surface of the hub body 30, there is provided an annular support portion 60 which protrudes inward in the radial direction.
Four outer races 22 are mounted. Bearing support sleeve 32
Is provided with an annular fixing portion 62 protruding radially outward at one end thereof, and the annular fixing portion 62 is fixed to the inner peripheral surface of the hub body 30 by, for example, press fitting. By mounting the bearing support sleeve 32 in this manner, an annular gap 64 is formed between the outer peripheral surface on the other end side of the bearing support sleeve 32 and the inner peripheral surface of the hub body 30, as shown in FIG. . The radial width of the annular gap 64 is set such that the outer peripheral surface of the bearing support sleeve 32 does not substantially contact the inner peripheral surface of the hub body 30 even when the temperature changes. Thereby, free thermal deformation of the other end side of the bearing support sleeve 32 is allowed. In this embodiment, one end surface (the lower end surface in FIG. 1) of the bearing support sleeve 32 has an annular fixing portion 6 of the hub body 30.
2 is attached to the hub body 30 so as to contact the hub body 30. Also,
The outer ring 22 of one bearing 14 is mounted so as to abut one end surface of the bearing support sleeve 32.

The outer ring 24 of the other bearing 14 is mounted on the other end of the bearing support sleeve 32, in this embodiment, at the other end and in the vicinity thereof. On the other end side of the bearing support sleeve 32, a large inner diameter portion 66 having an inner diameter larger than other portions is provided, and the outer ring 24 of the bearing 16 is mounted on the large inner diameter portion 66. By providing the large inner diameter portion 66 in this manner,
A shoulder 68 is formed adjacent to the large inner diameter portion 66, and the bearing 16 is mounted such that the outer ring 24 abuts the shoulder 68.

In this embodiment, the bearing support sleeve 32
Is formed from a material having a larger coefficient of thermal expansion than the shaft member 12. For example, when the shaft member 12 is formed from stainless steel (for example, SUS430F), the bearing support sleeve 32 is formed from aluminum (for example, A6061). The hub body 30 is formed of, for example, stainless steel (for example, SUS430F) or aluminum (for example, A6061), and the bracket 2 is formed of, for example, aluminum (for example, A6061).

For example, when the shaft member 12 is changed from SUS430F
When formed, the thermal expansion coefficient of the shaft member 12 is 10.4 × 1
0^-6/ ° C and the bearing support sleeve 32 is A6
061, the bearing support sleeve 32
Thermal expansion coefficient is 23.6 × 10 ^-6/ ° C, bearing support
The coefficient of thermal expansion of the sleeve 32 is smaller than the coefficient of thermal expansion of the shaft member 12.
Also increase.

In the spindle motor having the above-described structure, when the temperature of the motor itself rises due to a rise in the temperature of the recording disk drive, the balls 26 and 28 of the pair of bearings 14 and 16 are formed of a ceramic material. As described above, the inner and outer rings 18, 20, 22, 2
There is a tendency for a gap to occur between the four. On the other hand, in the relationship between the shaft member 12 and the bearing support sleeve 32, the thermal expansion coefficient of the bearing support sleeve 32 is larger than the thermal expansion coefficient of the shaft member 12. 32 has a larger thermal expansion. Therefore, based on one bearing 14, in the other bearing 16, the outer ring 24 is displaced more axially outward than the inner ring 20, that is, upward in FIG. 1. Such a displacement of the outer race 24, as will be readily understood, will result in bearings 14,
16 is a displacement in a direction in which the gap between the inner and outer rings 18, 20, 22, and 24 is eliminated. Therefore, by configuring as described above, the inner rings 18, 20 and the outer ring 2 when the temperature rises are increased.
The gap between the bearings 2 and 24 is corrected by the difference in the axial displacement between the inner ring 20 and the outer ring 24 of the other bearing 16, thereby preventing backlash and vibration during rotation and a reduction in preload of the bearing. Can be.

In the above embodiment, since the other bearing 16 is mounted on the large inner diameter portion 66 of the bearing support sleeve 32, when the bearing support sleeve 32 thermally expands, the shoulder 68 of the other bearing 16 is attached to the other bearing 16. Acts on the end face of the outer race 24, which ensures that the outer race 24 is displaced in the axial direction.

In such a spindle motor,
In order to secure a sufficient amount of thermal deformation of the bearing support sleeve 32, the annular fixing portion 62, which is a fixing portion thereof, is attached to one of the bearings 1.
It is desirable to fix to the hub body 30 in the vicinity of 4. With this configuration, the pair of bearings 14, 16
Even if the interval between them is small to some extent, the axial length of the bearing support sleeve 32 can be sufficiently ensured.

As can be understood from the above description, the portion that contributes to displace the outer ring 24 of the other bearing 16 in the axial direction when the temperature rises is a portion where the bearing support sleeve 32 and the hub body 30 are fixed (specifically, the fixing portion). , Bearing support sleeve 3
2 between the inner end face of the second annular fixing portion 62 and the outer ring 24 of the other bearing 16 (specifically, the end face of the shoulder 68 of the bearing support sleeve 32). (L) is preferably set to 0.85 ≦ L ≦ 7.83d (d: diameter of balls 26 and 28 as rolling elements). If the distance L is smaller than 0.85d, the inner and outer rings 18, 20, 22, 2
There is a gap between the four. On the other hand, if the interval L is larger than 7.83d, the axial displacement of the outer ring 24 of the bearing 16 at the time of temperature rise becomes larger than the gap generated at this time, and an excessive preload is applied. Become like In addition, the above-mentioned interval L is the inner ring 1 of the bearings 14 and 16.
8, 20, the outer rings 22, 24 and the materials of the balls 26, 28, the contact angles of the balls 26, 28, the materials of the shaft member 12 and the bearing support sleeve 32, and the like will vary somewhat.
For example, in a 3.5-inch hard disk spindle motor, the distance L is about 3 to 4 mm.
The gap between the outer peripheral surface of the bearing support sleeve 32 and the inner peripheral surface of the hub body 30 is about 1 mm. Second Embodiment FIG. 2 is a half sectional view showing a pair of bearings and their vicinity in a second embodiment of the spindle motor according to the present invention. In the following embodiments, members that are substantially the same as those in the first embodiment are given the same numbers, and descriptions thereof are omitted.

In the second embodiment, the bearing support sleeve is modified. Referring to FIG. 2, the illustrated bearing support sleeve 72 has a substantially cylindrical sleeve shape.
An annular fixing portion 74 is provided at one end thereof. In this embodiment, the outer diameter of one end of the bearing support sleeve 72 gradually increases in a tapered shape toward one end, and therefore, as shown in FIG. It protrudes in the direction. The hub body 3
When fixed to the inner peripheral surface of the bearing support sleeve 0 by, for example, press fitting, an annular gap 76 is formed between the outer peripheral surface of the bearing support sleeve 72 and the inner peripheral surface of the hub main body 30 at the other end of the bearing support sleeve. The bearing support sleeve 72 is mounted such that one end surface thereof comes into contact with the annular support portion 60 of the hub body 30.

Also in the second embodiment, the outer race 22 of one bearing 14 is mounted on the inner peripheral surface of the annular support portion 60 of the hub body 30, and the outer race 24 of the other bearing 16 is mounted on the bearing support sleeve 72. It is mounted on the inner peripheral surface on the other end side. In this embodiment, a first flange 78 protruding inward in the radial direction is provided at one end of the bearing support sleeve 72, and one of the bearings 14 is mounted so that the outer ring 22 abuts the first flange 78. You. A second flange 80 that protrudes inward in the radial direction is provided on the inner peripheral surface on the other end side of the bearing support sleeve 72, and the other bearing 16 is configured such that the outer ring 24 contacts the second flange 80. Be attached. By providing the second flange 80 in this manner, a shoulder is formed,
When the bearing support sleeve 72 thermally expands due to the temperature rise, the shoulder acts on the outer ring 24 of the other bearing 16. Other configurations of the second embodiment are substantially the same as those of the above-described first embodiment.

Also in the second embodiment, as easily understood by comparing FIGS. 1 and 2, the shaft member 12, the pair of bearings 14, 16 and the hub body 30 are easily understood.
Since the basic configuration of the bearing support sleeve 72 is substantially the same as that of the first embodiment, the same functions and effects as those of the first embodiment are achieved. Third Embodiment FIG. 3 is a half sectional view showing a pair of bearings and their vicinity in a third embodiment of the spindle motor according to the present invention.

In the third embodiment, the hub main body and the bearing support sleeve are modified. Referring to FIG. 3, the inner end of the annular support portion 60A of the illustrated hub main body 30A includes: A fixed protrusion 82 protruding inward in the radial direction is provided. The bearing support sleeve 84 has a substantially cylindrical sleeve shape, and is provided at one end thereof with a mounting flange 86 protruding inward in the radial direction.
An annular concave portion 88 is provided on the outer peripheral surface of one end of the bearing support sleeve 84 corresponding to No. 6. In this embodiment, one end of the bearing support sleeve 84 is fixed by, for example, press-fitting the circumferential side surface of the annular concave portion 88 into the inner circumferential surface of the fixed protrusion 82 of the hub body 30A. As shown in the figure, on the other end side of the bearing support sleeve 84, the outer peripheral surface of the bearing support sleeve 84 and the hub body 30
An annular gap 87 is formed between A and the inner peripheral surface. still,
The bearing support sleeve 84 is positioned by the end face of the annular recess 88 abutting on the end face (the upper end face in FIG. 3) of the fixed projection 82.

Also in the third embodiment, the outer race 22 of the bearing 14 is provided on the annular support portion 60 of the hub body 30A.
A is mounted on the inner peripheral surface of A, and the outer ring 22 is positioned at a predetermined mounting position by abutting against the end surface (the lower end surface in FIG. 3) of the fixed projection 82. The outer race 24 of the other bearing 16 is mounted on the inner peripheral surface on the other end side of the bearing support sleeve 84. In this embodiment, as in the first embodiment, a large-diameter portion 90 is provided on the other end side of the bearing support sleeve 84, and by providing the large-diameter portion 90 in this manner, a shoulder 92 is provided adjacent to the large-diameter portion 90. Is formed, and the other bearing 16 is formed.
Is mounted on the large-diameter portion 90 such that the outer ring 24 abuts the shoulder portion 92. Other configurations of the third embodiment are substantially the same as those of the first embodiment.

In the third embodiment, as easily understood by comparing FIGS. 1 and 3, the shaft member 12, the pair of bearings 14, 16 and the hub body 30 are easily understood.
The basic configuration of the bearing support sleeve 72 is substantially the same as that of the first embodiment, and the bearing support sleeve 84 is fixed to the hub body 30A at one end, and has an annular shape between itself and the hub body 30A at the other end. Since the gap 87 is formed, the same operation and effect as in the first embodiment are achieved. In addition, the outer race 22 of the bearing 14 and the bearing support sleeve 84 are fixed to the fixed projection 82 provided on the hub body 30A.
The outer ring 22 and the bearing support sleeve 84 can be accurately positioned with respect to the hub body 30A. Further, the bearing support sleeve 84
Is fixed to the inner peripheral surface of the fixing projection 82, so that the distance L between the fixing portion of the bearing support sleeve 84 and the mounting portion of the outer ring 24 of the bearing 16 can be increased. Fourth Embodiment FIG. 4 is a half sectional view showing a pair of bearings and their vicinity in a fourth embodiment of the spindle motor according to the present invention.

In the fourth embodiment, the bearing support sleeve is modified in comparison with the third embodiment described above. Referring to FIG. 4, the illustrated bearing support sleeve 102 is substantially It has a cylindrical sleeve shape, and at one end thereof is provided a mounting flange 104 protruding inward in the radial direction. An annular recess 106 is provided on the outer peripheral surface of the bearing support sleeve 102 corresponding to one end of the mounting flange 104. ing. One end of the bearing support sleeve 102 is formed by fixing the peripheral side surface of the annular concave portion 106 to the fixed projection 82 of the hub body 30A.
Is fixed to the inner peripheral surface of the bearing support sleeve 102 by, for example, press-fitting.
On the other end side of the hub, an annular gap 108 is formed between the outer peripheral surface of the bearing support sleeve 102 and the inner peripheral surface of the hub body 30A.
Is formed.

In the fourth embodiment, similarly to the third embodiment, the outer ring 22 of one bearing 14 is mounted on the inner peripheral surface of the annular support portion 60A of the hub body 30A, and the other is mounted on the other. The outer ring 24 of the bearing 16 is
2 is mounted on the inner peripheral surface on the other end side. In substantially the same manner as described above, the large-diameter portion 1 is provided on the other end of the bearing support sleeve 102.
10 is provided, adjacent to which a shoulder 112 is formed, and the other bearing 16 is mounted on the large bore 110 such that its outer ring 24 abuts the shoulder 112.

In the fourth embodiment, the bearing support sleeve 1
An annular groove 114 is provided on the outer peripheral surface of the predetermined portion 02. The annular groove 114 is provided at a fixing portion of the bearing support sleeve 102 with the hub body 30A (that is, the annular concave portion 1).
06) and the mounting portion of the bearing 16 (that is, the shoulder portion 112). By providing the annular groove 114 in this manner, the thickness of the bearing support sleeve 102 is reduced at the position of the annular groove 114, so that the bearing support sleeve 102 is easily bent in the axial direction. Other configurations of the fourth embodiment are similar to those of the third embodiment described above.
The embodiment is substantially the same as the embodiment.

In the fourth embodiment, the basic configuration is substantially the same as that of the third embodiment.
The same operation and effect as those of the embodiment are achieved. In addition, since the annular groove 114 is provided on the outer peripheral surface of the bearing support sleeve 102, it is easy to bend at the portion where the annular groove 114 is provided, thereby improving the preload applying effect and the preload maintaining effect. .

Although various embodiments of the spindle motor according to the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and corrections can be made without departing from the scope of the present invention. It is.

For example, in the illustrated embodiment, the outer ring 22 of the bearing 14 on the base side of the shaft member 12 is mounted on the hub body 30 (30A), and the outer ring 24 of the bearing 16 on the distal side of the shaft member 12 is provided. To the bearing support sleeve 32 (72, 8).
4, 102), but on the contrary, the outer ring 22 of the bearing 14 on the base side is connected to the bearing support sleeve 32.
(72, 84, 102) and the bearing 1
The outer ring 24 of No. 6 may be attached to the hub body 30 (30A). In this case, it is desirable to fix one end of the bearing support sleeve 32 (72, 84, 102) to the vicinity of the outer ring 24 of the bearing 16 on the distal end side.

[0049]

According to the spindle motor of the first aspect of the present invention, the coefficient of thermal expansion of the bearing support sleeve is larger than the coefficient of thermal expansion of the shaft member.
With reference to one bearing, the outer ring of the other bearing is displaced somewhat axially outward from its inner ring, that is, in a direction in which the gap generated in the radial direction is corrected by the axial displacement, and thus the ceramic rolling element is moved. It is possible to prevent the pre-load of the provided bearing from dropping at a high temperature.

According to the spindle motor of the second aspect of the present invention, when the other end of the bearing support sleeve thermally expands due to a temperature rise, the annular shoulder of the bearing support sleeve acts on the outer ring of one of the bearings, Thus, the outer ring of the bearing can be reliably displaced in the axial direction.

According to the spindle motor of the third aspect of the present invention, since the annular groove is formed on the outer peripheral surface of the bearing support sleeve, the bearing support sleeve is easily bent in the axial direction, so that the bearing is fixed to the pair of bearings. The preload applying effect of applying a preload and the preload maintaining effect of maintaining a predetermined preload at a high temperature are improved.

According to the spindle motor of the fourth aspect of the present invention, the axial length of the bearing support sleeve can be sufficiently ensured, and the outer ring of the other bearing is displaced as required at high temperatures. Thus, the preload of the pair of bearings can be reliably prevented from dropping out.

According to the spindle motor of the fifth aspect of the present invention, the bearing and the bearing support sleeve can be positioned at predetermined positions with respect to the hub body. The outer ring of the other bearing can be displaced as required at high temperatures by increasing the distance to the outer ring of the bearing mounted on the other.

Further, according to the spindle motor of the sixth aspect of the present invention, the clearance of the bearing caused by the temperature rise can be corrected by the displacement in the axial direction, and the preload can be prevented from being released.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a recording disk drive spindle motor according to the present invention.

FIG. 2 is a half sectional view schematically showing bearings and their vicinity in a second embodiment of a recording disk drive spindle motor according to the present invention.

FIG. 3 is a half sectional view schematically showing bearings and their vicinity in a third embodiment of a recording disk driving spindle motor according to the present invention.

FIG. 4 is a half sectional view schematically showing bearings and their vicinity in a fourth embodiment of a recording disk drive spindle motor according to the present invention.

[Explanation of symbols]

 2 Bracket 4 Rotor hub 6 Bracket body 12 Shaft member 14, 16 Bearing 18, 20 Inner ring 22, 24 Outer ring 26, 28 Ball (rolling element) 30, 30A Hub body 32, 72, 84, 102 Bearing support sleeve 42 Rotor magnet 44 Stator 64, 76, 87, 108 annular gap 68, 88, 112 shoulder

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshiki Okayama 248 Nakajuku, Aichigawa-machi, Aichi-gun, Aichi-gun, Shiga Prefecture F-term (reference) 5D109 BA04 BA14 BA18 BA20 BA28 BA32 BB04 BB05 BB16 BB21 BB27 BB32 BC14 5H605 BB05 BB14 BB19 CC04 DD05 EA06 EA13 EB10 EB17 EB36 EB37

Claims (6)

[Claims] A shaft member fixed to a base member of a recording disk drive device or a bracket attached to the base member;
A rotor hub on which at least one recording disk is mounted, a pair of bearings disposed at an axial distance between the shaft member and the rotor hub, a rotor magnet mounted on the rotor hub, In a spindle motor for driving a recording disk, comprising a stator disposed to face a rotor magnet, wherein the rotor hub is disposed inside a hub body on which the recording disk is mounted, and radially inside the hub body. A bearing support sleeve, one end of the bearing support sleeve is fixed to the inner peripheral surface of the hub body, between the outer peripheral surface of the other end side of the bearing support sleeve and the inner peripheral surface of the hub body. An annular gap is formed, and the pair of bearings are, respectively, an inner ring and an outer ring that are disposed at intervals in the radial direction, and between the inner ring and the outer ring. A plurality of ceramic rolling elements that are present, the outer ring of one of the pair of bearings is mounted on the hub body, and the outer ring of the other bearing is on the other end side of the bearing support sleeve. The bearing support sleeve has a thermal expansion coefficient greater than that of the shaft member, and when the temperature rises, the axial thermal expansion of the bearing support sleeve is greater than the axial thermal expansion of the shaft member. A spindle motor for driving a recording disk. 2. The recording disk drive according to claim 1, wherein an annular shoulder portion acting on an outer ring of the other bearing is provided on the inner peripheral surface on the other end side of the bearing support sleeve. Spindle motor. 3. The recording disk drive spindle according to claim 2, wherein an annular groove is formed on an outer peripheral surface of a portion between a fixing portion of the bearing support sleeve and the annular shoulder portion. motor. 4. The bearing support sleeve according to claim 1, wherein one end of said bearing support sleeve is fixed to said hub body in the vicinity of a bearing on a base side of said shaft member among said pair of bearings. A spindle motor for driving a recording disk according to any one of the above. 5. A predetermined portion of an inner peripheral surface of the hub body,
A fixed protrusion is provided to protrude inward in the radial direction, an outer ring of a bearing on a base side of the shaft member is positioned so as to abut one end surface of the fixed protrusion, and the bearing support sleeve is connected to the other end surface of the fixed protrusion. 5. The spindle motor for driving a recording disk according to claim 4, wherein the bearing support sleeve is positioned so as to abut against the inner peripheral surface of the fixing projection. 6. An axial distance (L) between a fixing portion of the bearing support sleeve and the hub main body and the outer race of the other bearing is 0.degree., Where d is a diameter of the rolling element.
6. The spindle motor for driving a recording disk according to claim 1, wherein 85d.ltoreq.L.ltoreq.7.83d.